1. Field of the Invention
The present invention relates to a chronograph timepiece having a zeroing structure. Particularly, the invention relates to a chronograph timepiece constituted to be able to firmly and simultaneously zero a chronograph hour hand, a chronograph minute hand and a chronograph second hand by a hammer.
2. Description of the Prior Art
(1) A Chronograph Timepiece of a First Type of a Prior Art
According to a chronograph timepiece of a first type of a prior art, when a reset button is depressed, a hammer transmission lever is rotated. By rotating the hammer transmission lever, a hammer is brought into contact with a second heart cam to zero a chronograph second hand. Further, when the reset button is depressed, an hour hammer transmission lever (A) is rotated. By rotating the hour hammer transmission lever (A), an hour hammer transmission lever (B) is rotated. By rotating the hour hammer operating lever (B), an hour hammer is brought into contact with a minute heart cam to zero a chronograph minute hand, simultaneously, brought into contact with an hour heart cam to zero a chronograph hour hand (refer to, for example, JP-A-11-23741).
(2) A Chronograph Timepiece of a Second Type of a Prior Art
According to a chronograph timepiece of a second type of a prior art, in resetting operation, when a button on a 4 o'clock side is depressed, a zeroing lever is rotated. By rotating the zeroing lever, a chronograph hammer is rotated. The chronograph hammer is brought into contact with three heart-like members to zero three hands (refer to, for example, Japanese Patent Publication No. 3336041).
(3) A Chronograph Timepiece of a Third Type of a Prior Art
According to a chronograph timepiece of a third type of a prior art, when a chronograph depressing member is depressed, a lever for hammer is operated. By operating the lever for hammer, three hammers of zeroing control members are respectively brought into contact with three cams to zero three hands (refer to, for example, JP-A-9-178868).
However, according to the chronograph timepieces of the prior arts, there are problems shown below.
(1) A Problem of the Chronograph Timepiece of the First Type of the Prior Art
According to the chronograph timepiece of the first type of the prior art, the chronograph second hand is zeroed by the hammer transmission lever and the hammer, the chronograph minute hand and the chronograph hour hand are zeroed by the hour hammer transmission lever (A), the hour hammer transmission lever (B) and the hour hammer and therefore, a number of parts constituting zeroing operation is large. Further, parts for zeroing the chronograph second hand and parts for zeroing the chronograph minute hand and the chronograph hour hand are separated from each other and therefore, much time is needed in assembling and adjusting the parts.
Further, according to the chronograph timepiece of the first type of the prior art, a clutch mechanism is provided at a surface train wheel. Further, a number of parts constituting a chronograph mechanism is large and the chronograph mechanism is complicated. Therefore, according to the chronograph timepiece of the first type of the prior art, there poses a problem of increasing a thickness of a movement.
(2) A Problem of the Chronograph Timepiece of the Second Type of the Prior Art
According to the chronograph timepiece of the second type of the prior art, a tolerance of a part of a portion at which the chronograph hammer is brought into contact with the heart-like member is severe and there is a necessity of individually adjusting the part in contact with the heart-like member in fabricating the chronograph hammer. That is, the chronograph hammer is rotated to be brought into contact with the three heart-like members simultaneously and therefore, it is very difficult to accurately control dimensions and shapes of the three parts of the chronograph hammer in contact with the heart-like members.
(3) A Problem of the Chronograph Timepiece of the Third Type of the Prior Art
According to the chronograph timepiece of the third type of the prior art, tolerances of parts of portions at which the three hammers of the zeroing members are brought into contact with the three cams are severe and there is a necessity of individually adjusting the portions in contact with the cams in fabricating the chronograph hammer. That is, the zeroing members are rotated to be brought into contact with the cams simultaneously and therefore, it is very difficult to accurately control dimensions and shapes of the three portions of the three hammers of the zeroing member in contact with the cams.